1. Field of the Invention
The present invention relates to a glycerol (medical grade) preparation method and more particularly, to a glycerol preparation method using a by-product of a bio-diesel process.
2. Description of the Related Art
It is known that making bio-diesel by transesterification of vegetable oil produces vegetable gel, crude glycerol, free fatty acid, methanol (or ethanol), and a saponified by-products consisting of potassium hydroxide.
These saponified by-products have commercial value, however they are harmful to the environment if they are not refined. Regular medium and small-scale bio-diesel refinery plants usually sell these by-products to the market at a price ranging from 200 to 250 US dollars per metric tone (fourth season, 2007) just because they have no technique or equipment to process these by-products.
There are companies which would provide special techniques for refining crude glycerol into refined glycerol. However, this investment takes a big amount of capital, few people make this investment. When received these by-products, most downstream manufacturers use a part of the by-products to make soap and then put the wastes into fuel oil for use as fuel, or prepare the wastes for making feed. Some other downstream manufactures may add these by-products to heavy fuel oil for use as fuel oil. The end products according to these methods have low added value. That's too bad.